In wireless (tele-)communication networks, a continuously active channel, e.g. between a mobile phone and a base-station, is preferable when the anticipated data transmission is continuous. With a continuously active channel, the user is able to efficiently transmit or receive a continuous data stream over the allocated active channel. However, the exploding increase of packet data applications, such as those used when communicating over the Internet, make allocating a continuously active channel to a single user an over allocation of resources. Control signals sent from a base station to a mobile station or messaging may occur only infrequently and it may not be desirable to allocate a continuously active channel for a limited purpose.
Accordingly, wireless networks may allow a signal to be transmitted discontinuously, i.e. communication to a receiver over a channel does not occur continuously, but may be cycled on and off. The interval during which the signal is not transmitted is generally referred to as DTX. The receiver is then faced with the problem of determining when a signal was transmitted, or when there is a lack of a signal, i.e. requires some DTX detection mechanism.
Under ideal circumstances the receiver would demodulate the transmitted signals as they arrive and realize that lack of a signal to demodulate indicates that the transmitter is engaging in DTX, and is in fact not transmitting a signal. However, a real world communication link does not operate under ideal channel conditions, nor does a real world receiver operate with an ideal demodulator. Thus, whilst a receiver may easily make detect DTX under ideal channel conditions, in reality signal multipath, fading, path loss, noise, and interference corrupt the signal incident on the receiver. Additionally, in reality the receiver demodulator will not exhibit ideal characteristics and not every received signal may be accurately demodulated. The result of this is that DTX non-ideal characteristics is that a receiver demodulating a continuously transmitted signal will occasionally be unable to recover the transmitted data unless computationally expensive DTX solutions are used.
Accordingly, known DTX detection systems either lack accuracy because designed for ideal circumstances or have a high computational overhead to cope with the real world operating circumstances.